"Essential's engineers are developing a proprietary connector that serves double duty for charging the battery and expanding the phone's functionality over time, one person familiar with the planning said. The magnetic connector would allow Essential or even third parties to create hardware accessories that add features to the smartphone. For instance, Rubin’s engineers are working on a sphere-shaped camera add-on that shoots high-resolution 360 degree photographs, the person said."

https://www.bloomberg.com/news/articles/2017-01-13/andy-rubin-nears-his-come...